Internal combustion engine



Patented Aug. 30, 1932 PATENT OFFICE WADIM S. MAKAROFF, OF NEW YORK, N. Y.

INTERNAL COMBUSTION ENGINE Application filed December 21, 1929. Serial No. 415,837.

This invention relates to internal combustion engines of the four cycle type and more particularly to improvements in the scavenging of engines of this type.

6 The advantages of improved scavenging have long been recognized and various arrangements have been proposed for this purpose, such arrangements having for their general object the reduction of the clearance space between the piston and the head of the cylinder at the termination of the exhaust stroke to more thoroughly expel the exhaust productions of combustion. In attempting to achieve this object prior inventors have employed relatively heavy compound pistons of various types, but in general consisting of a pair of pistons each having head v and skirt portions, these pistons being slit ably mounted with respect to each other and one of them being connected to the crank shaft in any usual manner. I

These arrangements are not practical for two principal reasons. In the first place the weight of two pistons will be practically twice the weight of a single piston of an engine of the ordinary type. This is a distinct disadvantage as the efforts of designers at the present time are in the direction of reduction of weight of pistons as far as possible consistent with other factors of engine design. In the second place, the outer piston which comprises a head and a skirt will, due to its excessive weight, develop at high speeds such a momentuinat the ends of its strokes that a system of heavy springs is provided 7 to overcome the effects of its inertia. These springs will not only add to the weight of the compound piston, but their resilience will be affected by the high temperatures in the cylinder. Even if they be designed for any a particular engine speed they will not be sultable for other speeds. other speeds, either the scavenging effect will be reduced or the momentum will not be adequately compensated.

It is an object of this invention to overcome the disadvantages of prior arrangements of the character described above for improving the scavenging of four cycle'internal combustion engines by providing a Therefore at such piston composed of a skirt section engaging the wall of the cylinder and connected in any suitable manner to the crank shaft, and a head section also engaging the wall of the cylinder, and variably connected to theskirt section so that at the termination of the scavenging stroke of the engine it contacts with the head of the cylinder to expel all waste products of combustion through the exhaust valve. The apparatus, therefore, avoids the duplication of parts which occur in those arrangements in which two relative-o ly movable pistons are employed, each of which has a head portion and a skirt portion, thereby greatly decreasing the weight of the piston as compared with prior devices for this purpose.

It is a further object of the invention to overcome the disadvantages attending the use of the springs employed in prior devices for regulating the relative movements between the two pistons. This object is attained by providing for a restricted flow of air into or out of the space between the head and skirt sections of the piston, the latter section be ing provided at its top with a relatively light partition provided with suitable orifices for restricting the flow of air and which also serves as a part of the movable connection between the head and skirt sections of the piston.

The particular nature of the invention as well as other objects and advantages thereof will appear more clearly from a description of a preferred embodiment thereof as illustrated in the accompanying drawing in which Fig. 1 is an elevation principally in section showing the position of the parts at the termination of the exhaust stroke, and

Fig. 2 is a similar view of the piston taken at right angles to the corresponding parts of Fig. 1.

In Fig. 1, 1 is a cylinder mounted upon a crank case 2 and provided with a head 3 having intake and exhaust valves 4 and 5 respectively. A piston 6 is provided with a skirt section 7 having a pin 8 to which is attached a connecting rod 9 also connected to a crank 10 of a crank shaft 11. The piston 6 is also provided with head section 12 having a contour corresponding to that the inner face of cylinder head 3. The piston head 12 is movably mounted on the skirt? by means of a hollow stem 18 extending through a sleeve 14 on a. partition 15 at the top of the skirt. The stem is provided at its lower end with a collar 16 by which the head is drawn down on descending stroke of the piston. The partition 15 is provided with a plurality of orifices 17 to permit ingress and egress of air to and from the space between the partition and the head of the piston. V

In the operation of the engine described above the momentum of the head 12 during upward movement of the piston on the crhaust stroke will, since the exhaust valve 5 is open to the atmosphere, cause it to move away from the sk'ilii'ulltll these parts occupy V the relative positions shown in the drawing "with the head in contact with the cylinder head. As the head 12 moves away from the skirt a partial'vacuum will be created between'them due to the restricted admission of air through the orifices 17 which will be so designed that at highest engine speeds the head 12 contacts with the cylinder head 3 with no excessive impact. At lower speeds the momentum of the head will be less, but

"the vacuum will be less because it is function of the speed of the piston therefore the scavenging effect willbe substantially the same at all speeds. his is not true-of springs for their resilience constant and does not change with changes in speed. The regulation of the force of the impact of the head 12 may also be obtained by suitable manipulation of the exhaust valve 5. As the skirt 7 moves downwardly on the following intake stroke it will carry with it the head 12 due to the engagement of the sleeve 14 with the collar 16. Due to its momentum the head will at the end of this stroke seat itself upon the top of the skirt. The gradual expulsion be avoided as there may be sufficient leakage of air through the orifices 1'? during thisstroke will retard the movement of the head and decrease its impact against the top of the skirt as it reaches the end of this stroke.-

During the following compression and working strokes the head will remain seated on the skirt due to the pressure existing in the space above the piston.

In some cases the use of the orifices 17 may between the inner surface of the cylinder and the rings 18 and 19 of the two sections of the piston to serve the same purpose.

While a preferred embodiment has been disclosed herein it will be understood that it may be embodied in other forms and that various changes may be made in detail of construction without departing from the principal of the invention as defined in the" appended claims.

I claim: 1. In an internal combustion engine, the

' combination of a cylinder having a head, a

exhaust stroke of the piston.

2. In an internal combustion engine, the combination of a. cylinder having a head, a piston in the cylinder composed of separate head and skirt sections each engaging the inner surface of the cylinder, a crank shaft, a connection between the skirt section and the crank shaft, and means connecting the head and skirt sections for permitting free relative movement therebetween whereby the clearance space between the head section and thehead of the cylinder is reduced during the exhaust stroke of the piston.

3. In an'internal combustion engine,-the

combination'of a cylinder having a head, a. piston in the cylinder composed of separate head and skirt sections each engaging the inner surface of the cylinder, said skirt section having a partition at itstop provided with an orifice for permitting a restricted'flow of air to and from the space between the head and skirt sections during relative movement therebetween, a crank shaft, a connection between one of the sections and the crank shaft...

and means connecting the head and skirt sections for permitting free relative movement therebetween whereby the clearance space between the head section and the head of the cylinder is reduced during the exhaust stroke of the piston.

4. In an internal combustion engine, the combination of a cylinder having a head, a piston in the cylinder com os ed of a skirt section provided with a partition at its top having a restricted aperture therein, and a. head section provided with an extension slidably and freel movable in the skirt section whereby t e clearance space between the head section and the head of the cylinder may reduced during the exhaust stroke of the piston by movement of the head section awa from the skirt section, means associated Wit the head section whereby it may be drawn along with the skirt section during the intakestroke of the piston, a crank shaft and 'a. connection between the skirt section and the crank shaft.

5. In an internal combustion engine, the combination of a cylinder having a. head, a piston in the cylinder composed of a skirt section provided with a partition at its top having an aperture therein, and a head section provided with an extension slidably mounted in the aperture, whereby the clear the sections and the crank ance space between the head section and the head of the cylinder may be reduced during the exhaust stroke of the piston by movement of the head section away from the skirt section, means associated with the head section whereby it may be drawn along with the skirt section during the intake stroke of the piston, said partition being provided with an jorifice for permitting a restricted flow of air to and from the space between the head and .skirt sections during relative movement therebetween, a crank shaft, a connection be tween one of the sections and the crank shaft and means connecting the head and skirt sections for permitting free relative movement vtherebetween whereby the clearance space between the head section and the head of the cylinder is reduced during the exhaust stroke of the piston.

6. In an internal combustion engine, the combination of a cylinder having a head, a piston in the cylinder composed of a head section engaging the inside of the cylinder and a skirt section engaging the inside of the cylinder and provided with a partition at its top, means associated with the head section and the partition for permitting free movement of the head section away from the skirt section to reduce the clearance space between the head section and the head of the cylinder during the exhaust stroke of the piston, means co-acting with said means whereby the head section may be drawn along with the skirt section during the intake stroke of the piston, a crank shaft and a connection between the skirt section and the crank shaft.

In testimony whereof, I hereby affix my signature.

WADIM S. MAKAROFF. 

